Make the following improvements and fixes:
1.
Update the Kinetis USB driver so that endpointReadResult only reads the
result of the last read and does not trigger a new read. Instead
move the code to trigger new reads into endpointRead.
2.
Fix the race condition in controlIn caused by a call to
EP0read() followed immediately by EP0readStage(). This is done by
setting up to read the next setup packet (ignoring the status stage)
in endpointReadResult rather than in EP0readStage. This makes the
function EP0readStage unnecissary.
3.
Remove the Kinetis workaround in controlOut in USBDevice.cpp since
point 2 fixes this bug. For more info on this see the PR which
added this workaround - https://github.com/ARMmbed/mbed-os/pull/414
The local static initialization in USB was causing multiple problems:
-Configurable descriptor values are set only once
-USB descriptor initialization causes a trap in debug builds since
this is acquiring a mutex in an interrupt handler
-Extra ram used since all descriptors are in RAM
This patch fixes these problems by making fixed descriptors
static const so they are stored in flash and never need to be
initialized and by making descriptors that do change a member
of the class so they are always initialized when requested
rather than once though lazy static local initialization.
Cruz Monrreal
Russ Butler
Christopher Haster